Re: Should MI be supported (was: Can MI be supported?)

[Matthew Heaney <matthewjheaney@earthlink.net>]

Lionel.DRAGHI@fr.thalesgroup.com writes:

> That's where we differ. I feel much more confortable with Bob's
> translation, because Colorable is not an object, it's a "properties".

Perhaps, but I felt (and still do) that my translation was more faithful
to the C++ example.


> My_Adapter is an Adapter, so inheritance applies.  My_Adapter is not a
> "colorable", so i won't inherit from some colorable class.  Neither is
> "Colorable" a particular "role" of an Adapter.

What's interesting is that my example, I only exposed the root interface
types: Colorable_Type and Resizeable_Type.  I felt that in Hyman's
implementation, he exposed too much information; specifically, that
My_Object derived from Colorable_Adapter_Type and
Resizeable_Adapter_Type.

But that's only an implementation detail.  What's nice in the approach I
showed is that you only have to advertise that you support the root type
interface.  The fact that privately I "inherited" from
Colorable_Adapter_Type and Resizeable_Adapter_Type was only an
implementation detail, and therefore I was able to move it to the
private part of the spec.

Hyman: Is there a way to do that in C++?  Can you publicly inhterit from
ColorableType and privately inherit from ColorableAdapterType?


> It's just a characteristic (note that Colourable is an adjective,
> Adapter is a noun), and so i use a Mixin.  You may perfectly use
> multiple views if you feel better with it. Hyman choose MI instead of
> (templates + SI) because the code was simpler to write.  But in my
> opinion, mixin translate better the problem description.

The mixin approach may translate better to the problem description, but
it's debatable whether it translates better to the C++ implementation.
As usual, YMMV....